\[\frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a}\]
Test:
NMSE problem 3.2.1, positive
Bits:
128 bits
Bits error versus a
Bits error versus b/2
Bits error versus c
Time: 21.9 s
Input Error: 34.7
Output Error: 6.0
Log:
Profile: 🕒
\(\begin{cases} \frac{\frac{\frac{1}{2} \cdot c}{\frac{b/2}{a}} - \left(b/2 - \left(-b/2\right)\right)}{a} & \text{when } b/2 \le -2.326207163052239 \cdot 10^{+115} \\ \frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a} & \text{when } b/2 \le -1.9116038778178358 \cdot 10^{-274} \\ \frac{c}{\left(-b/2\right) - \sqrt{b/2 \cdot b/2 - c \cdot a}} & \text{when } b/2 \le 4.449432714488087 \cdot 10^{+57} \\ \frac{c}{\left(\frac{1}{2} \cdot c\right) \cdot \frac{a}{b/2} - 2 \cdot b/2} & \text{otherwise} \end{cases}\)

    if b/2 < -2.326207163052239e+115

    1. Started with
      \[\frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a}\]
      48.8
    2. Using strategy rm
      48.8
    3. Applied add-exp-log to get
      \[\frac{\left(-b/2\right) + \color{red}{\sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\left(-b/2\right) + \color{blue}{e^{\log \left(\sqrt{{b/2}^2 - a \cdot c}\right)}}}{a}\]
      49.8
    4. Applied taylor to get
      \[\frac{\left(-b/2\right) + e^{\log \left(\sqrt{{b/2}^2 - a \cdot c}\right)}}{a} \leadsto \frac{\left(-b/2\right) + e^{\log \left(\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - b/2\right)}}{a}\]
      16.6
    5. Taylor expanded around -inf to get
      \[\frac{\left(-b/2\right) + e^{\log \color{red}{\left(\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - b/2\right)}}}{a} \leadsto \frac{\left(-b/2\right) + e^{\log \color{blue}{\left(\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - b/2\right)}}}{a}\]
      16.6
    6. Applied simplify to get
      \[\frac{\left(-b/2\right) + e^{\log \left(\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - b/2\right)}}{a} \leadsto \frac{\frac{\frac{1}{2} \cdot c}{\frac{b/2}{a}} - \left(b/2 - \left(-b/2\right)\right)}{a}\]
      1.4

    7. Applied final simplification

    if -2.326207163052239e+115 < b/2 < -1.9116038778178358e-274

    1. Started with
      \[\frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a}\]
      8.9

    if -1.9116038778178358e-274 < b/2 < 4.449432714488087e+57

    1. Started with
      \[\frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a}\]
      28.9
    2. Using strategy rm
      28.9
    3. Applied flip-+ to get
      \[\frac{\color{red}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\color{blue}{\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}}{a}\]
      29.1
    4. Applied associate-/l/ to get
      \[\color{red}{\frac{\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}{a}} \leadsto \color{blue}{\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)}}\]
      33.7
    5. Applied taylor to get
      \[\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)} \leadsto \frac{c \cdot a}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)}\]
      22.0
    6. Taylor expanded around inf to get
      \[\frac{\color{red}{c \cdot a}}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)} \leadsto \frac{\color{blue}{c \cdot a}}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)}\]
      22.0
    7. Applied simplify to get
      \[\frac{c \cdot a}{a \cdot \left(\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}\right)} \leadsto \frac{\frac{c}{1}}{\left(-b/2\right) - \sqrt{b/2 \cdot b/2 - a \cdot c}}\]
      10.2

    8. Applied final simplification
    9. Applied simplify to get
      \[\color{red}{\frac{\frac{c}{1}}{\left(-b/2\right) - \sqrt{b/2 \cdot b/2 - a \cdot c}}} \leadsto \color{blue}{\frac{c}{\left(-b/2\right) - \sqrt{b/2 \cdot b/2 - c \cdot a}}}\]
      10.2

    if 4.449432714488087e+57 < b/2

    1. Started with
      \[\frac{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}{a}\]
      58.3
    2. Using strategy rm
      58.3
    3. Applied flip-+ to get
      \[\frac{\color{red}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\color{blue}{\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}}{a}\]
      58.3
    4. Applied simplify to get
      \[\frac{\frac{\color{red}{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\frac{\color{blue}{a \cdot c}}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}{a}\]
      32.4
    5. Applied taylor to get
      \[\frac{\frac{a \cdot c}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\frac{a \cdot c}{\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - 2 \cdot b/2}}{a}\]
      15.2
    6. Taylor expanded around inf to get
      \[\frac{\frac{a \cdot c}{\color{red}{\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - 2 \cdot b/2}}}{a} \leadsto \frac{\frac{a \cdot c}{\color{blue}{\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - 2 \cdot b/2}}}{a}\]
      15.2
    7. Applied simplify to get
      \[\color{red}{\frac{\frac{a \cdot c}{\frac{1}{2} \cdot \frac{c \cdot a}{b/2} - 2 \cdot b/2}}{a}} \leadsto \color{blue}{\frac{c}{\left(\frac{1}{2} \cdot c\right) \cdot \frac{a}{b/2} - 2 \cdot b/2}}\]
      1.6

  1. Removed slow pow expressions

Original test:


(lambda ((a default) (b/2 default) (c default))
  #:name "NMSE problem 3.2.1, positive"
  (/ (+ (- b/2) (sqrt (- (sqr b/2) (* a c)))) a))